Research into night habits of primary school children finds link between noisy sleepers and behaviour If your child is not doing well in school and gets cranky easily, check whether he or she snores at night, a paediatrics expert says. Associate Professor Albert Martin Li, of Chinese University, who specialises in sleep-related breathing disorders, found that children who snore are twice as likely to be hyperactive and perform poorly in school than those who sleep peacefully. There is also a 75 per cent higher chance that they will be bad-tempered. The findings emerged from a 2002-03 study of 6,471 primary school pupils aged between six and 13 at Sha Tin and Tai Po. Responses from parents showed that 7.1 per cent of the children snored at least three nights a week, which is regarded as habitual snoring. It was projected that at least 30,000 primary school pupils across the city were habitual snorers. The figures did not include children in international schools. Snoring is also a risk factor in obstructive sleep apnoea, a condition in which a person stops breathing temporarily because of a blocked airway. Dr Li said this could be linked to the development of hypertension and could affect brain development in children as their oxygen supply was obstructed. Analysis of data from the study, believed to be the largest of its kind worldwide, is expected to be completed in six months, after which a report will be published. The findings showed that 23 per cent of children with a snoring problem had a poor academic performance, compared to 13.5 per cent of those who did not snore. Thirty-five per cent of those who snored had poor temper control and 23 per cent were found to be hyperactive. For children who did not snore habitually, only 20.8 per cent were found to be bad-tempered and 13.7 per cent were hyperactive. Dr Li said children lacked concentration and lost their temper easily during the day if they were deprived of quality sleep due to snoring. However, the study did not show a strong link between snoring and weight, as those with snoring problems had a mean weight of 36kg, only about 2kg more than those who did not snore. Dr Li said snoring was commonly associated with tonsil or adenoid enlargement, common in children under 10. 'We believe that Chinese people, who usually have flat facial features, are at a higher risk of airway obstruction that gives rise to snoring and even sleep apnoea ... We also suspect that genetic factors play a role,' he added. Dr Li said parents should take their children to the doctor if they had snoring problems to check if they suffered from sleep apnoea. The condition can be treated by removing the tonsils or adenoids, or with a machine that blows air into the nose via a mask, keeping the airway open.